Currently most authentication methods of authentication systems on the market still focus on accounts and passwords. Despite the convenience of such mechanism, the security is rather poor. Hackers may obtain or crack passwords, especially for passwords easily guessed or remembered, through a variety of methods. Password strength is also a big issue for passwords itself. The higher safety password which is relatively not easy to be remembered may still have high possibility that cannot reach hacker prevention and instead unable the users to log in. Each network or system needs passwords, some systems may request users to change their passwords regularly and causing users often forget their passwords. Therefore, many people still choose to use passwords easy to remember, but by contrast, the password safety is greatly declined.
Even if the abovementioned password strength is high enough, it can not prevent completely from hacker's violent invasion and scanning crack. For the safety of the clients, most of the financial websites and game websites will use additional authentication tools. The authentication tool is not convenient to use; due to it is usually an extra hardware, it is even more inconvenient to carry. It will bother user for unable to log in the system if the authentication tool is not carried or lost. In addition, to provide users with authentication tools, it will cost the business owners a certain amount of expense in developing the authentication tool. However, the most inconvenient point is that the authentication tools are exclusive technologies and there is no shared or united method for authentication; therefore, the consumers may need to carry many authentication tools at the same time. Although recently Google also provided a kind of portable USB hardware for authentication, it still faces the above problem that is not convenient to be carried and lost easily.